Structured hot water demand flow control system with expansion tank

ABSTRACT

In a hot water system for providing intermittent hot water, a separate holding vessel is provided and disposed in a hot water line between a hot water source and a plumbing fixture for blending of incoming hot water with residual water in the vessel in order to decrease cold water surges at the plumbing fixture upon repeated use of hot water in the plumbing fixture. A bladder disposed within the separate holding vessel accommodates for thermal expansion of the water and positioning of vessel inlets and outlets prevents stagnation of water in the vessel.

This application is a continuation-in-part of U.S. Ser. No. 12/048,545 filed Mar. 14, 2008 which is continuation-In-part of U.S. Ser. No. 11/602,071 filed Nov. 20, 2006. These applications are to be incorporated herein in their entirety by this specific reference thereto.

The present invention is generally directed to plumbing systems and is more particularly directed to plumbing systems of high thermal efficiency.

Certain types of water heaters, for example, gas tankless water heaters, after being shut down and restarted allow cold water to flow through the water heater for a number of seconds before the burners are able to bring the temperature up to the water heater set point. This creates a cold water “plug” or “sandwich” effect in hot water line. That is, the hot water line, while still full of mostly hot water, experiences several seconds during which cold water flows through the water heater before the burners start to fire up and heat the water, thus creating the cold water “plug” or “sandwich”.

In addition, modern plumbing codes often mandate backflow prevention. In this case, thermal expansion can cause pressure buildup in water systems. When demand is put upon a potable water system, hot water is drawn from the water heater. Cold water from the supply line enters the water heater to replenish it. The cold water is heated to replace the hot water used. With the installation of a backflow preventer, check valve or pressure reducing valve on the supply line, the water heater and the system piping from a closed plumbing system under pressure. As the water is heated, thermal expansion occurs. Pressure increases until the relief valve opens and the expanded water spills from the water heater or the water heater ruptures. This spillage results in wasted energy and a potential safety hazard.

The use of a convention expansion tank, such as, for example set forth in U.S. Pat. No. 4,784,181 introduces yet another problem in potable water systems in that stagnant water accumulates in the expansion tank which thereafter may contaminate the entire water system.

The present invention minimizes the sandwich effect and accommodates for thermal expansion of the water without water stagnation.

SUMMARY OF THE INVENTION

The present invention provides for an improvement in a hot water system and a system which provides intermittent and hot water. This system includes a hot water source, at least one plumbing fixture and a hot water line interconnecting the hot water source and plumbing fixture.

The improvement in accordance with the present invention provides for a separate holding vessel which is disposed in the hot water line between the hot water source and the plumbing fixture which, in turn, provides for blending of incoming of hot water with residual water in the vessel in order to decrease cold water surges, otherwise known as “plugs” or “sandwiches”, at the plumbing fixtures upon repeated use of the hot water at the plumbing fixture. The vessel has a volume of water for a given length greater than the volume of water in the hot water line for the given length.

In order to prevent a stagnant build up of water within the vessel, a vessel water inlet and water outlet are disposed on one side of a bladder. This is to be contrasted with conventional expansion tanks with a bladder-type diaphragm that has only one port, for both ingress and egress of water. This type of expansion tank retains a stagnant amount of water, particularly when small pressure/temperature differentials occur in an interconnecting line.

Preferably, the vessel is disposed proximate the hot water source which may be a tankless hot water heater.

In one embodiment of the present invention, the system includes a recirculating line interconnected with the plumbing and fixture and hot water source for circulating cold water at the plumbing fixture back to the hot water source.

In another embodiment of the present invention, the system includes a cold water line interconnected with the plumbing fixture and a valve disposed proximate the plumbing fixture and interconnecting the hot and cold water lines, for enabling circulation of cold water to the hot water source.

In this embodiment, the system may further include a pump in fluid communication with the valve and the hot and cold water lines for circulating water from the hot water line into the cold water line.

In yet another embodiment in accordance with the present invention the holding vessel may incorporate a bladder for sealing a gas within a portion of the vessel which accommodates thermal expansion of water in its system.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will appear from the following description when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram of plumbing system which provides for circulation of cold water back to the hot water source upon demand in which the improvement according to the present invention is incorporated;

FIG. 2 is a diagram of a plumbing system in accordance with the present invention which does not include a circulation of water in which the present improvement is employed; and

FIG. 3 is a diagram of a plumbing system in accordance with the present invention utilizing a bladder disposed in a separate holding vessel for accommodation, or absorbing, thermal expansion of water in the system.

DETAILED DESCRIPTION

With reference to FIG. 1, there is shown a hot water recovery system 10 which generally includes a hot water source 12, which may be a gas or electric tankless water heater or a conventional gas or electric water heater, connected to a plumbing fixture such as a sink 14 by a hot water delivery line 16. Also provided in a conventional manner is a cold water delivery line 18 interconnecting the sink 14 with a cold water source 20 which is also interconnected with the hot water source 12 via a feed line 22.

Optional plumbing fixtures such as sinks 28, 30 and washing machine 32 may be provided along with any other common plumbing fixture utilized in residences and businesses, all such fixtures being connected in a parallel configuration with the hot water delivery line 16 and cold water delivery line 18 by feed lines 40 and 42, respectively. At a selected plumbing fixture, such as the sink 14 which is most remote from the hot water source 12, a pump 46 may be interconnected between the hot water delivery line 16 and the cold water delivery line 18 via the feed lines 40, 42 respectively. The pump provides means for circulating water from the hot water delivery line 16 through the cold water delivery line 18 and back into the hot water source 12 via line 22, by utilizing the cold water delivery line as a return feeder to the hot water source 12. No separate circulation line need be implemented in new systems. In order for the pump 46 to effect flow in a reverse manner through the cold water delivery line 18 and into the hot water source 12, the pump 46 must, of course, develop sufficient head to overcome existing water pressure in the line.

A control system 50, which may be of any common electrical type employing relays or solid state electronics or microchips, provides a means for switching electrical current outlet 52 to pump 46 in order to cause the pump 46 to circulate water from the hot water line 16 to the cold water line 18.

A temperature sensor 54 is disposed in a line 56 interconnecting the pump 46 with the hot water delivery line 16 through the feed line 40, providing means for causing the control means to stop the pump 46 to prevent heated water from being circulated through the cold water delivery line 18 as will be hereinafter described. The temperature sensor 54 may be of a conventional type inserted into the line 56 for water flow thereover, or it may be a thermistor type of detector strapped to the outside of the line 56. The sensor 54 may be of a type for detecting a selected water temperature and in response thereto causing the control system to stop the pump 46.

The temperature sensor 54 may be configured for detecting a temperature increase, or gradient, such as one or two degrees and in response thereto, causing the control system 50 to stop the pump 46. Thus, no matter what the actual temperature of the water in the line 56 is, an increase of one or two degrees will cause the pump 46 to stop. The pump 46 is started through the control system 50 by means of optional manual switches 60 electrically connected to the control system 50 by way of wires 62 for causing the control system to turn on the pump 46, the control system in this manner acting as a relay switch. Alternatively, to reduce electrical wiring costs, a flow detector 64 may be disposed in the hot water delivery line 18 at any position and connected to the control system by an electrical wire 66 for causing the control system 52 to turn on the pump 46 in response to a detection of a water flow in the hot water delivery line 18.

Although the flow detector 64 is shown adjacent to the hot water source 12, it may be alternatively disposed in the line 40 beneath the sink 14 for reducing the electrical interconnection required and for enabling all of the apparatus of the present invention to be disposed beneath the sink 14. Either the manual switches 60 or flow detector 64 enables the control means 52 to turn on the pump 46 when a hot water valve 70 on the sink 14 is turned on, thus causing a flow in the hot water delivery line 18.

It should be appreciated that if the pump 46 is not a positive displacement type which does not allow water to flow in a reverse manner through it, then a one-way valve 70 should be provided to prevent such flow and preferably a solenoid 72, controlled by the control system 50, should be inserted upstream of the pump 46 to prevent water flow through the pump 46 when the control system 50 turns off pump 46.

It should also be appreciated that the temperature sensor 54 should be disposed in the hot water line or attached to it as hereinbefore described to prevent a rescission between the hot water delivery line 16 and the cold water delivery line 18, However, the pump can be located anywhere throughout the system 10 between the hot water delivery line 16 and cold water delivery line 18.

The improvement in accordance with the present invention includes a separate holding vessel 80 disposed in the hot water line 16 between the hot water source 12 and the sink 14. The holding vessel 80 functions for blending of incoming hot water with residual water in the vessel in order to decrease cold water surges at the sink 14 upon repeated use of hot water at the plumbing fixture.

As can be seen, FIG. 1 vessel 80 has a diameter greater than the hot water line 16 and accordingly has a volume of water per given length greater than a volume of water in the hot water line 16 for the given length.

With reference to FIG. 2, there is shown an improvement of vessel 100 in accordance with present invention as it may be used in a hot water system 102 which includes a hot water source, or heater, 104, plumbing fixtures 106, 108, 110, 112, and a hot water line 120 interconnecting the water heater 104, which may be a tankless water heater or a tank water heater, and fixtures 106, 108, 110, 112, cold water is provided to the water heater 104 by a cold water line 122. Shown in dotted line, for a tankless water heater 104, a separate holding vessel 100 a may be installed within a housing 114 of the heater 104. As with the earlier described in the system 10, the improvement vessels 100, 100 a as shown has volume of water per given length greater than the volume of water in the hot water line 120.

With reference now to FIG. 3, there is shown a hot water system 130 in accordance with the present invention for providing intermittent hot water and, as diagramed, common elements with substantially the same or identical structure to elements shown in FIG. 3 are designated by common character references.

In this embodiment, a separate holding vessel 134 is disposed in the hot water line 120 between the hot water source 104 and fixtures 106, 108, 110, 112 which functions for blending of incoming hot water with residual water in the vessel 134 in order to decrease cold water surges at the plumbing fixtures 106, 108, 110, 112 upon repeated use of hot water at the plumbing fixture 106, 108, 110, 112. As hereinabove discussed in connection with earlier described embodiments, the vessel 134 has a volume of water greater than the volume of water in the hot water line 120 for the length or dimension of the vessel 134.

While the vessel 134 is depicted as rectangular block, it should be appreciated that and suitable shape/configuration may be utilized.

In addition, a bladder 138 is disposed within the vessel 134 for sealing a gas 140 therein which accommodates for thermal expansion of water in the water system. The gas is compressed in a conventional manner upon expansion of water within the vessel 134 thus preventing damage to the hot water system 130, or heater 104, or release of water from the system through a leader valve (not shown).

A vessel water inlet 144 and a vessel water outlet 146 are disposed on one side 150 of the bladder 138 for transfer of water through the vessel 134. The water transfer causes combined flushing of the vessel 134 and thus eliminates or drastically reduces any possibility of water stagnation.

A gas inlet 154 may be provided for establishing and maintaining an appropriate pressure on another side 156 of the bladder 138 to enable suspension of the bladder 138 within the vessel in order to provide for accommodation of transient outer pressure variable and thermal expansion of water.

Although there has been hereinabove described a specific structured hot water demand flow control with accommodation for thermal expansion in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage? it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of, or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims. 

1. In a hot water system for providing intermittent hot water, the system including a hot water source, at least one plumbing fixture and a hot water line interconnecting said hot water source and said plumbing fixture, an improvement comprising: a separate holding vessel disposed in said hot water line between said hot water source and said plumbing fixture, for blending of incoming hot water with residual water in the vessel in order to decrease cold water surges at said plumbing fixture upon repeated use of hot water at said plumbing fixture, said vessel having a volume of water per given length greater than a volume of water in said hot water line for the given length; a bladder, disposed in said separate holding vessel and sealing a gas therein, for accommodation thermal expansion of water in the water system in order to prevent damage to the water system including the hot water source, or release of water from the system; and a vessel water inlet and water outlet both disposed as one side of said bladder.
 2. The improvement according to claim 1 further comprises a vessel gas inlet disposed on another side of said bladder.
 3. The improvement according to claim 2 wherein the vessel is disposed proximate said hot water source.
 4. The improvement according to claim 2 wherein said hot water source comprises a tankless hot water heater.
 5. The improvement according to claim 2 wherein the vessel is disposed within a housing of the tankless hot water heater.
 6. The improvement according to claim 2 wherein the system further comprises a re-circulating line interconnected said plumbing fixture and said hot water source for circulating cold water at said plumbing fixture back to said hot water source.
 7. The improvement according to claim 2 wherein the system further comprises a cold water line interconnected with and said plumbing fixture and a valve, disposed proximate said plumbing fixture, interconnecting the hot and cold water lines, for enabling circulation of cold water to said hot water source.
 8. The improvement according to claim 7 wherein the system further comprises a pump in fluid communication with said valve and hot and cold water lines for circulating water from said hot water line into said cold water line.
 9. A hot water system for providing intermittent hot water, the system comprising: a hot water source; at least one plumbing fixture; a hot water line interconnecting said hot water source and said plumbing fixture; and a separate holding vessel, disposed in said hot water line between said hot water source and said plumbing fixture, for blending of incoming hot water with residual water in the vessel in order to decrease cold water surges at said plumbing fixture upon repeated use of hot water at said plumbing fixture, said vessel having a volume of water per given length greater than a volume of water in said hot water line for the given length; a bladder, disposed in said separate holding vessel and sealing a gas therein, for accommodation thermal expansion of water in the water system in order to prevent damage to the water system including the hot water source, or release of water from the system; and a vessel water inlet and water outlet both disposed on one side of said bladder.
 10. The system according to claim 9 farther comprising a vessel gas inlet disposed on another side of said bladder.
 11. The system according to claim 10 wherein the vessel is disposed proximate said hot water source.
 12. The system according to claim 10 wherein said hot water source comprises a tankless hot water heater.
 13. The system according to claim 12 wherein the vessel is disposed within a housing of the tankless hot water heater.
 14. The system according to claim 10 wherein the system further comprises a re-circulating line interconnected said plumbing fixture and said hot water source for circulating cold water at said plumbing fixture back to said hot water source.
 15. The system according to claim 10 wherein the system further comprises a cold water line interconnected with and said plumbing fixture and a valve, disposed proximate said plumbing fixture, interconnecting the hot and cold water lines, for enabling circulation of cold water to said hot water source.
 16. The system according to claim 15 wherein the system further comprises a pump in fluid communication with said valve and hot and cold water lines for circulating water from said hot water line into said cold water line. 